It is easy question. Wherever you can find people is good starting point. I was shooting from my car when i first started. It feels better but hard to get good pictures out of it. You can park on a good spots before shooting. Don’t forget to pay for parking. You can get a ticket. My camera always on when i am driving. Especially, on the red light you can see something worth shooting. This picture is taken from my car. Fortunately, my camera is on my lap and ready to shoot. I also shot the girl with bike (you can see the picture below) from my car. If you are just started, i advise you to go to beach. You will find people more peaceful than other places. It will give peaceful state and even you started to like more to photographing people you do not know.